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The Inga–Shaba HVDC represented one of the United States' most important third world commitments of the 1970s and 1980s. However, construction progress was plagued by rebel insurgency in Southern Zaire, massive logistical challenges, large cost overruns, and financing delays.

By utilizing the hydroelectric potential of the Inga Dam and by constructing one switching station near Kinshasa at Selo, the Government of Zaire under Mobutu Sese Seko was theoretically able to control the flow of power to secession-prone Katanga, then Shaba, province, but never actually exercised this option. It was reported in La Libre Belgique, a Brussels newspaper, that Tractionel, a Belgian electrical contractor, had argued that more economical alternatives were available nearer Shaba, using low-head generator plants, but had been overlooked in favor of the American consortium, consisting of Morrison-Knudsen International as a prime contractor, and Swedish ASEA, Italian Sadelmi-Cogepi and Irish GE subsidiary as sub-contractors.

The project was initially conceived as a US$250 million contract - but cost overruns, partly due to unanticipated armed conflict in Shaba Province, pushed the final price up over US$1 billion, with unofficial estimates ranging as high as US$1.3 billion, inclusive of a comprehensive Operations and Maintenance Contract.[2]

Construction of the Inga–Shaba Project provided the Ministry of Energy and the Société nationale d'électricité (SNEL), with the means to promote further development activity throughout Zaire, by attracting potential investors and overseas firms; however, there have been suggestions that well-placed officials in the Mobutu government may have accepted gratuities at various critical junctures during the construction phase.[3] As the Republic became more indebted to overseas financial entities, the Inga–Shaba Project ultimately accounted for approximately 20% of the former Zaire's debt burden, the total amount of which was $5 billion at the time, according to a variety of credible sources.

This scheme, equipped from the outset with thyristor valves provided by Swedish subcontractor ASEA, was designed to transmit 560 megawatts, in the first phase, at a symmetrical bipolar voltage of ±500 kilovolts. Although not the first 500 kV HVDC project in operation (the ±533 kV Cahora Bassa scheme having been completed in 1977) it was the first such scheme to use only a single twelve-pulse bridge per pole. Consequently its thyristor valves were the highest-rated in the world (in terms of voltage) at the time and remained so until the completion, in 2007, of the ±450 kV, single-converter NorNed scheme.[5] The thyristor valves for Inga Shaba had 258 thyristors in series in each valve and were air-insulated and air-cooled.[1]

Inga Shaba was the longest HVDC transmission line in service until 2010, when it was overtaken by the 2071 km, ±800 kV, 6400 MW HVDC link from Xiangjiaba Dam to Shanghai in China. Because the line runs through relatively inaccessible terrain, an unusually broad right-of-way was cleared, at considerable expense, to ensure tower integrity.

The line operated initially at only 10% of capacity. In the 1990s, prior to major social unrest, the line increased its power transmission to 200 MW, still considerably below design capacity. As of 2000, reliability had been poor with many thyristor failures at the inverter station.[6] As of 2010, the line was still functional as far as Bandundu, the capital of Bandundu province, approximately 400 kilometres (250 mi) northeast of Kinshasa.[citation needed] In 2009 ABB was awarded a contract to refurbish and modernise the converter equipment. This upgrade is due to be completed in 2013.